A method and system for operating a vehicle that includes an integrated starter/generator and a driveline disconnect clutch is described. In one example, the method estimates engine torque as a function of engine temperature during cold engine starts so that if an estimate of engine torque is in error, the integrated starter/generator may still successfully start the engine.
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2. The method of claim 1, further comprising adjusting torque of the electric machine in response to a torque that is a blend of the estimated engine torque and the fraction of the estimated engine torque.
3. The method of claim 2, where torque of the electric machine is adjusted in response to the torque that is the blend of the estimated engine torque and the fraction of the estimated engine torque a predetermined amount of time since a most recent start of an engine.
4. The method of claim 1, further comprising adjusting torque of the electric machine in response to an electric machine speed error.
5. The method of claim 4, further comprising applying a proportional/integral controller to the electric machine speed error.
6. The method of claim 1, where the second condition is the engine temperature less than the threshold temperature.
7. The method of claim 1, where the estimated engine torque is further based on spark timing.
9. The vehicle system of claim 8, further comprising additional instructions to adjust torque of the electric machine in response to an electric machine speed error.
10. The vehicle system of claim 9, further comprising additional instructions to apply a proportional/integral controller to the electric machine speed error.
11. The vehicle system of claim 8, further comprising additional instructions to multiply the first engine torque estimation value and a value of one minus the weighting factor.
13. The method of claim 12, further comprising adjusting torque of the electric machine in further response to an engine torque estimate that is a function of engine air flow and speed.
14. The method of claim 13, further comprising modifying the speed error via a proportional/integral controller.
15. The method of claim 14, where the electric machine is an integrated starter/generator.
16. The method of claim 12, wherein the engine torque estimate that is not a function of engine air flow and engine speed is a function of an engine temperature.
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August 3, 2020
April 4, 2023
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